In recent years, concerns have been raised about the potential danger of synthetic pesticides to humans and other non-target organisms. With this increased concern about toxicity and environmental safety, there has been a renewed interest in the use of safer substances, including natural active ingredients, for pest control. Chelating agents have a long history of human use and are widely used in the food, cosmetic and pharmaceutical industries. One of the best known pharmaceutical uses of chelating agents is in the treatment of heavy metal poisoning (Remington's Pharmaceutical Sciences). Chelating agents are also used extensively as stabilizers because they prevent oxidation of susceptible compounds by sequestering metal ions, which can catalyze degradation reactions.
Metal chelates are reported in the literature as control agents for molluscs (slugs and snails). For example, U.S. Pat. No. 5,437,870 (Puritch et al.) discloses an ingestible molluscicide having a carrier (e.g., a bait), a simple iron compound, and ethylene diamine tetracetic acid (EDTA), salts of EDTA, hydroxyethylene triamine diacetic acid, (HEDTA) or salts of HEDTA. U.S. Pat. No. 6,352,706 of Puritch also discloses an ingestible molluscicide containing a simple metal compound, an activity enhancing additive such as ethylene diamine disuccinic acid (EDDS) and derivatives thereof, and a carrier material edible to molluscs. Australian Patent Application No. 77420/98 of Young also discloses a stomach-action molluscicide that includes a metal complexone (i.e., iron EDTA) and a carrier.
The herbicidal (weed), algaecidal (algae) and fungicidal (plant disease) activity of metal chelates is also reported. For example, U.S. Pat. No. 6,323,153 of Smiley teaches using various chelated calcium and magnesium salts to control the growth of various weeds in lawns. Smiley also discloses, in U.S. Pat. No. 6,117,823, the use of aliphatic carboxylic acid diesters, such as dimethyl succinate and dimethyl glutarate, as non-selective herbicides. Further examples include U.S. Pat. No. 6,258,750 of Simpson, which teaches an algaecidal, herbicidal and/or fungicidal composition including a metal, the chelating agent ethylene diamine disuccinic acid (EDDS) or a salt thereof, and a source of calcium and chloride ions.
While the use of metal chelates and chelating agents in molluscicides, herbicides, algaecides, and fungicides is known, there is still a need for an environmentally safe pesticidal formulation for controlling insect pests.